Technical Field
The present disclosure relates to a transmitter. More particularly, the present disclosure relates to a transmitter with an elimination mechanism of a pulling effect and an eliminating method thereof.
Description of Related Art
In various wireless communication systems, a transmitter can modulate the frequency, by using an oscillating signal generated from an oscillator, to generate a radio frequency signal that is suit for the wireless communication. However, as the sizes of transmitters become smaller and smaller, such radio frequency signals may be incidentally coupled back to the oscillator. As a result, a phase error may be introduced into the oscillating signal, and thus the overall performance of the transmitter is reduced. The aforementioned phenomenon is commonly known as the “pulling effect.”
In some approaches, the calibration mechanism for eliminating the pulling effect is arranged subsequent to a mixer. As a result, the required bandwidth for such calibration mechanism may be too high. The cost and complexity of the transmitter are thus increased. In some other approaches, a calibration circuit for eliminating the pulling effect is arranged in a phase locked loop. As a result, unwanted phase noise may be introduced to reduce the performance of the transmitter.